A major part of your marketing automation is email marketing – communicating with your list of prospects and nurturing them into becoming valuable customers. This means that you need to build a list and doing so wisely is a hard work.

Ideally, you have selected the right email marketing provider, created your sign up forms and welcome emails and are now ready to start collecting the most valuable information – the contact details of your website visitors. You have just one last major decision to make before launching everything – single or double opt-in! And it is one of the hardest you will ever make.

There are a lot of Pros and Cons for both of those options and you need to choose wisely – not that you can’t switch them afterwards. The different impacts that single and double opt-ins have on your list are really important and your decision depends on your main goal.

What is the difference between single and double opt-ins?

The main thing that distinguishes those two options is whether you ask your new leads to confirm that they indeed want to receive your emails AFTER they signed up via a form. A single opt-in means that you don’t ask them to go to their email, find your message and click on the confirmation link/button. You can start sending emails directly. A double opt-in¬†works differently – when a new contact is recorded in your database, the system sends out an automated message that includes a confirmation link or button. Unless the receiver clicks on it, he won’t receive any of your messages – they would simply not be sent to him by your system.

Single Opt-in

Many marketing experts prefer to stay away from single opt-in (especially if working with Canadian customers). But there are positive impacts to your list, if you decide to use this method. Here are the Pros on using single opt-in:

  • Your list is bigger – Most people would skip or totally miss your double opt-in confirmation, which results in a lot of missed opportunities.
  • You spare one additional step – By not asking them to go to their inbox, find your email and click on the link, you are more likely to not annoy your new prospects.

The single opt-in is a great starter way for building your list – I say “starter” because it focuses on list growth and I don’t find it sustainable enough for a bigger list. Here are the Cons to using it:

  • More likely to be marked as SPAM – Your email messages are more likely to end up in their spam folder (at least unless they add you to their contact list – which almost nobody does nowadays).
  • Fake/false emails – Spammers would fill up your forms, but never read or receive your messages. Some folks would not realize they didn’t enter their email address correctly. Both of those types of contacts are unusable, irrelevant and a generator of higher bounce rates.
  • Less deliverability – It is not a secret that Email Service Providers (ESPs are those services you use to send email messages to your list) send out messages to single opt-in lists from a different IP address than the double opt-in. It is a matter of higher SPAM scores, high number of complaints and bounces. And if your email has lower chance of hitting the inbox of the recipient, then the chances of it being read are close to none.
  • Lower open and click through rates – All of the above leads to lower results and stats. And those are the numbers that would let you know if your campaign was good or bad. This might make the effectiveness of your message seem low even if it actually worked for your most valuable leads.

Double Opt-in

The double opt-in is dreaded by both you and your contacts. It requires and extra step – and your list of active subscribers grows a lot slower because of the high number of unconfirmed email addresses. What makes double opt-in better than single opt-in:

  • Higher deliverability – Your ESP is saving his best IP addresses for those lists as the bounces and complaints are much lower. Your emails have a higher chance of hitting the inbox and being read.
  • More engaged leads – If I’m willing to spare a second and confirm my subscription, I obviously care about what you want to say to me. Or your great lead magnet.
  • Higher open and click through rates – Real people who are engaged with your content would open and click on the CTAs in your message a lot more than those spammers who left their junk mail address and forgot about it.
  • A clean and valuable list – Would you prefer 10 000 people on your list with only 2% engagement rate (200 people) or a 1000 people with over 50% CTR? Everyone would prefer a smaller and more engaged list because this means your messages are open and read and this usually leads to more sales. The people on your double opt-in list wanted to follow up with you, confirmed their email and are waiting for your messages. I call the list clean because it contains real email addresses – if a message was delivered and open, then the overall bounce rate in time would be almost nonexistent. And lower bounce rates mean higher email scores – and better deliverability.


If you like the positive aspects of both options and you are trying to find a way to combine them, there is one. Even two.

Optional Double Opt-in – Not all email marketing software solutions offer this but it is important to know how it works. When your new lead signs up, he receives the confirmation email, but is not taken to the confirmation instructions page. This contact is counted and recorded as a single opt-in. However, as soon as the person clicks on the confirmation link in the email, he is switched to a double opt-in. If you offer a lead magnet, the best way is to postpone the email that delivers the free content with 5 to 10 minutes. This allows for the customer to be waiting eagerly for the message and the possibility that he will confirm his subscription increases.

Opt-in sequences – If you don’t have the option to do an optional double opt-in, try with a nurturing sequence. In the footer of the email you can add a short message asking for a confirmation, including the confirmation link. Chances are that some people (the most engaged) would click on it. The more you try and wait, the more double opt-ins you would get.

In conclusion, whether you decide to go with a single or double opt-in confirmation, there would always be Pros and Cons. The important thing is for you to decide what is the main goal in the current moment – a bigger list or a cleaner list.